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| index | Vol. 51 | 1 | 2/3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | Japanese Index | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Paleomagnetic Study of Neogene Rocks Around the Uozu Area, Eastern Part of Toyama Prefecture
Hiromi IWAKI(Graduate School of Engineering, Doshisha University) and Yasuto ITOH(Department of Earth Sciences, College of Integrated Arts and Sciences, Osaka Prefecture University)
2000
vol. 51 (6) P.229-236
6 figs, 1 table
Keywords: Uozu, Toyama, Southwest Japan, magnetostratigraphy, Miocene, clockwise rotation
Abstract : We made magnetic measurements of Neogene volcanic and sedimentary rocks in the Uozu area. All the samples from the Iwaine and Yatsuo formations have reversed primary remanent magnetization. Considering biostratigraphic data and lithological information, this sequence is assigned to the Kurosedani and Higashibessho formations distributed in the Yatsuo area, and is correlated with Chron C5BR of geomagnetic polarity timescale. The mean magnetic direction of the Yatsuo formation shows less eastward deflection than that of the Iwaine formation. This result suggests that the Yatsuo formation was formed during the clockwise rotation of Southwest Japan.
Measurement of archeomagnetic intensity of bricks from a Roman ruin in Slovakia
Tomoko OGISHIMA(Mejiro Gakuen High School), Rie MORIJIRI(Geophysics Dept., GSJ) and Naoko UENO(Natural Science Laboratory, Toyo University)
2000
vol. 51 (6) P. 237-249
8 figs, 5 tables
Keywords: Archeomagnetic intensity, Thelliers' method, Slovakia, Roman ruin
Abstract :Paleomagnetic intensity of bricks from a Roman ruin in Slovakia dated as 2nd-3rd century A.D. was measured. The Thelliers' method with triple heatings was applied to two bricks named sample A and B. The paleointensity from sample A was measured at the Toyo University and National Institute of Polar Research. The results from the two laboratories agreed roughly with the average of 60.7}7.6T. The paleointensity from sample B was 51.4}15.0T, which was measured at the Toyo University. The magnetic properties suggest that the larger scatter of sample B compared with sample A is possibly caused by heterogeneous oxidization created during the baking process of the sample B brick.
Origin of enclaves and sulfur in the Inada Granite, Tsukuba District, central Japan
Shunso ISHIHARA(Geological Survey of Japan) and Masahide KONO(Takata Co., Ltd)
2000
vol. 51 (6) P. 251-258
2 figs, 1 table, 2 plates
Keywords: Tsukuba, late Cretaceous, ilmenite-series granite, skarn, xenolith, pyrrhotite, 34S value
Abstract : Many enclaves with various sizes have been known to occur in granite quarries at Inada where Inada building stones are mined. They are mostly hornfels of fine-grained sandstones with some slates and limestones. None of them appears to be restites but derived from the roof sedimentary rocks at high level of the granitoid emplacement. Thus, they can be called xenolith. Unique pyrrhotite-rich ball enclaves were also found in the Inada granite quarries. They yielded negative 34S values around -10 permil, and are considered to be sulfides from not a deep source but shallow source of the pelitic wall rocks, which were originally concentrated in euxenic sediments of the basement accretionary complex. Because of sulfur-rich nature, the enclave became melt in the magma chamber after the entrapment, and thus became spherical forms.
Abstracts for Geological Survey Seminar, no. 266
Evaluation researches of earthquake occurrence potential by active faults and other factors
2000
vol. 51 (6), P. 259-266
Abstracts for Geological Survey Seminar, no. 267
Deltas: their Dynamics, Facies and Sequences with special references to sea-level changes and human impacts
2000
vol. 51 (6), P. 267-282
